This invention relates to a deposition method, a deposition apparatus, and a pressure-reduction drying apparatus for depositing a coating film on a substrate to be processed by supplying a liquid to the substrate and volatilizing a solvent from a liquid film.
Conventionally a spin coating method has been used widely in a deposition process using a liquid. Recently it has been the urgent necessity to develop a scan coating method for forming a liquid film all over the surface of a substrate by moving an ultrathin nozzle and a substrate relative to each other in a column direction and moving them relative to each other in a row direction except for the top of the substrate in order to reduce an amount of liquid used for environmental protection and prevent coating irregularities in a peripheral portion due to an increase in the size of a substrate.
A conventional scan coating method has the problem that the thickness of a coating film formed by the method is made extraordinarily greater than a target value in a coating starting portion in a scan pitch direction and gradually decreases in a coating ending portion.
The object of the present invention is to provide a deposition method which is capable of uniforming the distribution of thicknesses of a coating film formed by a scan coating method.
In order to attain the above object, the present invention is constituted as follows.
(a) A deposition method comprises:
a liquid film forming step of dropping a liquid, which contains a solvent and solid matter added to the solvent, to a substrate to be processed from a dropping nozzle such that a fixed amount of liquid diffuses on the substrate, and moving the dropping nozzle and the substrate relative to each other with the dropped liquid remaining on the substrate, thereby to form a liquid film extending from a dropping starting point of the substrate to a dropping ending point thereof; and
a step of removing the solvent from the liquid film to form a coating film,
wherein, in the liquid film forming step, the substrate is heated or cooled to correct a temperature distribution of the liquid film caused by heat of evaporation due to volatilization of the solvent contained in the liquid film.
(b) A deposition method comprises:
a liquid film forming step of dropping a liquid, which contains a solvent and solid matter added to the solvent, to a substrate to be processed from a dropping nozzle such that a fixed amount of liquid diffuses on the substrate, and moving the dropping nozzle and the substrate relative to each other, with the dropped liquid remaining on the substrate, to drop the liquid from a dropping starting point of the substrate to a dropping ending point thereof, thereby to form a liquid film on the substrate; and
a step of removing the solvent from the liquid film to form a coating film whose surface is flat,
wherein, in the coating film forming step, the substrate is heated or cooled to correct a temperature distribution of the liquid film caused by heat of evaporation due to volatilization of the solvent contained in the liquid film.
The following are modes of operation which arc favorable for the above two methods.
The substrate is heated or cooled such that a temperature of the dropping starting point of the substrate becomes higher than that of the dropping ending point thereof
The substrate is heated or cooled such that an outer region of the substrate monotonously decreases in temperature from the dropping starting point to the dropping ending point and an inner region thereof is set at an almost fixed temperature, the almost fixed temperature being lower than a temperature of the dropping starting point and higher than that of the dropping ending point.
The substrate is heated or cooled so as to eliminate a temperature gradient of a region between the dropping starting point and the dropping starting point.
The substrate is heated or cooled such that a temperature gradient of the dropping ending point of the substrate becomes greater than that of the dropping starting point thereof.
The substrate is heated or cooled such that a temperature of both end portions of the substrate becomes lower than that of a central portion thereof.
The dropping starting point corresponds to a central portion of the substrate and the dropping ending point corresponds to end portions of the substrate; and
the liquid film forming step comprises a step of dropping a liquid from the central portion of the substrate to one of the end portions thereof and a step of dropping a liquid from the central portion to other of the end portions.
The liquid is one of a resist film agent, an antireflective film agent, a low dielectric film agent, and a ferroelectric film agent.
(c) A deposition apparatus comprises:
a dropping nozzle for supplying a liquid to a substrate to he processed;
a driving section for moving the substrate and the dropping nozzle relative to each other; and
a temperature controller on which the substrate is mounted, for providing a temperature distribution from a dropping starting point of the substrate to a dropping ending point thereof.
(d) A pressure-reduction drying apparatus comprising:
a temperature controller on which a substrate to be processed is mounted, for providing a temperature distribution from a liquid dropping starting point of the substrate to a liquid dropping ending point thereof; and
a pressure-reducing chamber holding the substrate and the temperature controller and connected to a vacuum pump.
The following are modes of operation which are favorable for the above two apparatuses.
The temperature controller includes:
a heat absorbing section for absorbing heat and a heat generating section for generating heat, each of the heat absorbing section and the heat generating section being constituted of a plurality of plates whose temperatures are controlled independently; and
a thermal diffusion plate provided on the heat absorbing section and the heat generating section.
The temperature controller includes:
a plurality of outer plates for independently controlling temperatures of a plurality of areas of an outer region of the substrate;
a central plate for controlling a temperature of a central region of the substrate;
a thermal diffusion plate provided on the outer plates and the central plate; and
a gap adjustment table which is provided on the thermal diffusion plate and on which the substrate is mounted to form a gap between the thermal diffusion plate and the substrate.
The temperature controller includes:
a plurality of outer plates for independently controlling temperatures of a plurality of areas of an outer region of the substrate;
a thermal diffusion plate provided on the outer plates and a central plate; and
a gap adjustment table which is provided on the thermal diffusion plate and on which the substrate is mounted to form a gap between the thermal diffusion plate and the substrate.
The above-described invention has the following advantages.
The nonuniformity of thickness of a film formed by volatilizing a solvent from a liquid film is caused by temperature profile due to the heat generated by the evaporation of the solvent after a liquid is dropped. The nonuniformity of thickness can be suppressed by forming a liquid film on the substrate having a temperature distribution for correcting the distribution of temperatures profile.
The nonuniformity can also be suppressed by making the temperature of a dropping starting point of the substrate higher than that of a dropping ending point thereof.
The nonuniformity can be suppressed more greatly by setting a temperature gradient of the dropping ending point greater than that of the dropping starting point.
Furthermore, the nonuniformity can be suppressed by eliminating a temperature gradient of a region between the dropping starting and ending points.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.